Compatibilizing agent for polycarbonate and polyamide polymer blends

ABSTRACT

A compatibilizing agent for polymeric blends of polycarbonates and polyamides which have improved physical and chemical resistance properties, without any substantial sacrifice of the desirable properties of the polycarbonate or polyamide. The polymeric compatibilizing agent has at least one functional group soluble in the polycarbonate and at least one functional group soluble in the polyamide, and preferably is a polymeric compatibilizing agent for blends of polycarbonate and polyamide resins, which comprises from about 10 to 90 or even 100 weight percent of a compound selected from the group consisting of a polyetherimide, a polyurethane and a linear segmented thermoplastic elastomers having an ester segment and a hard segment of semi-crystalline, partially aromatic polyamide, based on diphenylmethane diisocyanate; from about 90 to about 10 weight percent of a maleic anhydride grafted polymeric blend; from 0 to about 80 weight percent of an alloying agent; said compatibilizing agent thus having at least one functional group soluble in the polycarbonate resin and at least one functional group soluble in the polyamide resin; wherein the melting or softening point of said compatibilizing agent is no greater than the melting or softening points of the polycarbonate and polyamide resin constituents in the blend. A process for producing the polymeric blends of a polycarbonate and a polyamide is also provided.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of application Ser. No. 915,239, filed Oct. 3, 1986, now abandoned.

TECHNICAL FIELD

The present invention relates generally to a compatibilizing agent for polymeric blends of polycarbonates and polyamides wherein the melt compounded blend has improved physical and chemical properties, and to a process for preparing such blends.

BACKGROUND ART

Polymeric resins have long been known for their chemical and physical properties. Molded or extruded resins have found numerous applications, such as in appliances, consumer products, electronics, machine components, automotive parts and the like. However, the physical and chemical properties of the polymeric resins, and thus the components or articles fabricated therefrom, vary widely depending upon the chemical structure of the main chain or backbone of the polymeric resins, as well as the molecular weight of such polymeric resins.

For example, polycarbonate resins are known to possess desired heat distortion temperatures, but suffer in that such polymeric resins, and thus articles molded or extruded therefrom, generally possess low chemical resistance to solvents, low stress crack resistance, and low impact strength when thick sections of the polymer are required or utilized. On the other hand, polymeric resins, such as the polyamides (i.e. the nylons), are known to be chemically resistant to a large number of solvents, and to have a desired degree of toughness and abrasion resistance. However, the polyamide polymers also possess certain inherent disadvantages, unless modified, such as relatively low impact strength, a low heat distortion temperature, and an affinity to pick up moisture.

In order to modify the properties of polymeric resins, mixtures of selected polymeric resins have been utilized to form blends. However, it many cases, such as with polycarbonate and polyamide resins, such resins are incompatible. Attempts to render such resinous materials compatible have generally involved expensive chemical compounds or process conditions, and even then the resulting resinous blend often does not possess the desired properties. Therefore, it would be highly desirably and a significant advance in the art if an efficient and economical process or compatibilizing agent could be found which could render polycarbonate resins compatible with polyamide or nylon resins, without sacrificing the desired properties of each of the resinous materials forming the blend.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a compatibilizing agent for polycarbonate and polyamide resins which thus enables an improved polymeric blend of these materials to be obtained without a substantial sacrifice of the desirable properties of each of the resins employed in the blend.

Another object of the present invention, while achieving the before stated object, is to provide an inexpensive process for producing such polymer blends of polycarbonates and polyamides by the use of conventional mixing equipment.

Other objects, advantages and features of the present invention will become clear from the following detailed description when read in conjunction with the appended claims.

Accordingly, the present invention relates to a compatibilizing agent for polymeric blends of polycarbonates and polyamides which agent allows the blend to achieve improved physical and chemical resistance properties, without any substantial sacrifice of the desirable properties of the polycarbonate or polyamide. These polymeric blends possess the desired properties of each of the constituents forming the blend, namely, the blend has improved resistance to solvents and stress crack agents, a relatively high impact strength and heat distortion temperature, and the polymeric blends do not have an affinity to absorb moisture.

The polymeric blend of a polycarbonate and a polyamide, such as nylons, havng the before-mentioned properties generally comprises from about 20 to about 90 weight percent of a polycarbonate having a molecular weight of from about 20,000 to about 40,000, from about 70 to about 5 weight percent of a linear polyamide having a molecular weight of at least about 2,000, and from about 20 to about 2 weight percent of a polymeric compatibilizing agent having at least one functional group soluble in the polycarbonate and at least one functional group soluble in the polyamide.

The polymeric compatibilizing agent for such blends of polycarbonate and polyamide resins generally comprises from about 10 to 90 weight percent of a compound selected from the group consisting of a polyetherimide, a polyurethane and linear segmented thermoplastic elastomer having an ester segment and a hard segment of semi-crystalline, partially aromatic polyamide, based on diphenylmethane diisocyanate; from about 90 to about 10 weight percent of a maleic anhydride grafted polymeric blend; and from about 0 to about 80 weight percent of an alloying agent. Preferably, the melting or softening point of the compatibilizing agent is no greater than the melting or softening points of the polycarbonate and polyamide resin constituents of the blend.

The present invention also provides a process for producing a polymeric blend of a polycarbonate and a polyamide which comprises: (a) mixing from about 20 to about 90 weight percent of a polycarbonate having a molecular weight of from about 20,000 to about 40,000 with from about 70 to about 5 weight percent of a linear polyamide having a molecular weight of at least about 2,000, and from about 20 to about 2 weight percent of a polymeric compatibilizing agent having at least one functional group soluble in the polycarbonate and at least one functional group soluble in the polyamide for an effective period of time to produce a substantially homogeneous mixture; and (b) introducing the homogeneous mixture into a compounding extruder to produce a polycarbonate-polyamide melt compounded blend having the desirable properties of each of the constituents forming the blend. The compounding extruder is operated at a temperature above the melting temperature of the constituents of the polymeric blend, and at extensive shear so as to provide for improved mixing of the components of the blend and substantially uniform dispersement of the constituents throughout the blend.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The term "blend" as used herein is to be understood to signify a substantially homogeneous mass of materials, and the resulting extrudate, preferably in pellet form, which is obtained by heating such materials to the melting or softening point under high shear conditions in an extruder.

The blends of the present invention, which unexpectedly possess the desired chemically and physically properties of each of the constituents, generally comprise from about 20 to about 90 weight percent of a polycarbonate, from about 70 to about 5 weight percent of a linear polyamide, and from about 20 to about 2 weight percent of a polymeric compatibilizing agent having at least one functional group soluble in the polycarbonate and at least one functional group soluble in the polyamide. Such compatibility agents are generally block copolymers and blends containing such block copolymers wherein the block copolymer functions as an interfacial element between the two incompatible components.

The polycarbonates which can employed in the formulation of the blends of the present invention are well known in the art, and can be any suitable polycarbonate having a molecular weight preferably of from about 20,000 to about 40,000. Similarly, the linear polyamides which can be employed in the formulation of the blends of the present invention are also well known in the art and embrace those semi-crystalline and amorphous resins having a molecular weight of at least 2,000, commonly referred to as nylons. Desirably, the polyamide resins will have a molecular weight of at least about 5,000, and includes such polyamides as polycaprolactam (6 nylon), polyhexamethylene adipamide (66 nylon, polyhexamethylene azelamide (69 nylon) and the like.

In order for the polycarbonate constituent to be compatible with the polyamide constituent of the blend the polymeric compatibilizing agent must have at least one functional group soluble in the polycarbonate and at least one functional group soluble in the polyamide. The amount of the polymeric compatibilizing agent incorporated into the blend can vary widely, but will generally be in an amount of from about 2 to about 20 weight percent of the blend. Further, since it is desirable that the blend be melt compounded it is important that the melting or softening point of the polymeric compatibilizing agent preferably be no greater than the melting or softening point of the polycarbonate and polyamide constituents of the blend.

Any suitable compound satisfying the above-described criteria can be employed as the polymeric compatibilizing agent in the formulation of the polycarbonate-polyamide blends of the present invention. However, desirable results can be obtained when the polymeric compatibilizing agent comprises (a) from about 10 to 90, preferably between 15 and 75, and more preferably between 20 and 55 weight percent of a polyetherimide, a polyurethane or a linear segmented thermoplastic elastomer hving an ester segment and a hard segment of semi-crystalline, partially aromatic polyamide, based on diphenylmethane diisocyanate (such as the elastomers marketed by Dow Chemical Company under the trademark "Estamide 90A"; (b) from about 90 to 10, preferably 75 to 20, and more preferably 60 to 40 weight percent of maleic anhydride grafted polymeric blend; and (c) from 0 to about 80, preferably 25 to 75, and more preferably 30 to 50 weight percent of an alloying agent. It is also possible to utilize the polyetherimide, polyurethane or linear segmented thermoplastic elastomer as the sole compatibilizing agent (i.e., in an amount of up to 100%). According to another embodiment of the invention, the polymeric compatibilizing agent comprises mixtures of from about 25 to about 50 weight percent of the polyetherimide, polyurethane, or linear segmented thermoplastic elastomer having an ester segment and a hard segment of semi-crystalline, partially aromatic polyamide, from about 25 to about 50 weight percent of the maleic anhydride grafted polymeric blend, and from 0 to about 50 weight percent of the alloying agent.

The blends of the invention include a polyetherimide of the formula: ##STR1## where a represents a whole number in excess of 1, e.g., 10 to 10,000 or more, the group ##STR2## is selected from: ##STR3## R' hydrogen, lower alkyl or lower alkoxy, preferably the polyetherimide includes the latter ##STR4## group where R' is hydrogen such that the polyetherimide is of the formula: ##STR5## and the divalent bonds of the --O--Z--O radical are in the 3,3'; 3,4'; 4,3' or the 4,4' position; Z is a member of the class consisting of (1) ##STR6## and (2) divalent organic radicals of the general formula: ##STR7## where X is a member selected from the class consisting of divalent radicals of the formulas: ##STR8## where q is 0 or 1, y is a whole number from 1 to 5; and R is a divalent organic radical selected from the class consisting of (1) aromatic hydrocarbon radicals having from 6-20 carbon atoms and halogenatd derivatives thereof, (2) alkylene radicals and cycloalkylene radicals having from 2-20 carbon atoms, C.sub.(2-8) alkylene terminated polydiorganosiloxanes, and (3) divalent radicals included by the formula: ##STR9## where Q is a member selected from the class consisting of ##STR10## and x is a whole number from 1 to 5 inclusive. Particularly preferred polyetherimides for the purposes of the present invention include those where ##STR11## and Z respectively are: ##STR12## and R is selected from: ##STR13## The polyetherimides where R is metaphenylene are most preferred.

The polyurethane which can be employed as the polymeric compatibilizing agent in the polycarbonate-polyamide blends of the present invention are characterized as polyester urethane elastomers or the reaction products of polyesters and diisocyanates having a melting point less than the processing range used for compounding the compositions of the invention, i.e. 480° F. to 550° F. Illustrative of polyurethanes having the before-described characteristics, and which can be employed as the compatibilizing agent in the polymeric blends of the present invention are "PS 195-300", "PN-03-100" and "PS 440-100" polyurethanes manufactured by K. J. Quinn Company, and the like.

The maleic anhydride grafted polymeric blends which can be employed as the compatibilizing agent in the polycarbonate-polyamide blends of the present invention include blends of maleic anhydride grafted polypropylene or maleic anhydride grafted ethylene propylene, and these can be prepared by any suitable grafting techniques known in the art. Further the amount of the maleic anhydride grafted polypropylene and the maleic anhydride ethylene-propylene rubber present in the grafted polymeric blend constituent of the polymeric compatibilizing agent can vary widely. However, the maleic anhydride grafted polypropylene rubber will generally be present in the grafted polymeric blend in a weight ratio of from about 0:1 to about 5:2, preferably in a ratio of between 1:3 to 3:1, and most desirably in a weight ratio of about 3:2.

The alloying agent which may be utilized as one of the constituents of the polymeric compatibilizing agent in the polycarbonate-polyamide blends can be any suitable alloying agent which is compatible with the polycarbonate, the polyamide and the other constituents comprising the polymeric compatibilizing agent. Generally, the alloying agents which can be employed as a constituent of the polymeric compatibilizing agent are characterized as thermoplastic resins compatible with either the polyamide, the polycarbonate, or both, and which improves properties of the overall polymeric blends of the invention, such as cost, impact strength, and processability. Examples of such thermoplastic resins which can be employed as the alloying agent are acrylonitrile-butadiene-styrene terpolymers, styrene-maleic anhydride copolymers, polyester elastomers, methacrylate-butadiene-styrene terpolymers, polymethylmethacrylate, nitrile rubber, ionomers of polyethylene, polyether block amides, polyphenylene oxide polymers and the like, as well as mixtures thereof.

The polyetherimides can be obtained by any of the methods well known to those skilled in the art including the reaction of any aromatic bis(ether anhydrides) of the formula ##STR14## where Z is a defined hereinbefore with an organic diamine of the formula

    H.sub.2 N--R--NH.sub.2

where R is as defined hereinbefore.

Aromatic bis(ether anhydride)s of the above formula include, for example, 2,2-(bis[4-(2,3-dicarboxyphenoxy)phenyl]propane dianhydride; 4,4'-bis(2,3-dicarboxyphenoxy)diphenyl ether dianhydride; 1,3-bis(2,3-dicarboxyphenoxy)benzene dianhydride; 4,4'-bis(2,3-dicarboxyphenoxy)diphenyl sulfide dianhydride; 1,4-bis(2,3-dicarboxyphenoxy)benzene dianhydride; 4,4'-bis(2,3-dicarboxyphenoxy)benzophenone dianhydride; 4,4'-bis(2,3-dicarboxyphenoxy)diphenyl sulfone dianhydride; etc., 2,2-bis[4-(3,4-dicarboxyphenoxy)phenyl]propane dianhydride; 4,4'-bis(3,4-dicarboxyphenoxy)diphenyl ether dianhydride; 4,4'-bis(3,4-dicarboxyphenoxy)diphenyl sulfide dianhydride; 1,3-bis(3,4-dicarboxyphenoxy)benzene dianhydride; 1,4-bis(3,4-dicarboxyphenoxy)benzene dianhydride; 4,4'-bis(3,4-dicarboxyphenoxy)benzophenone dianhydride; 4-(2,3-dicarboxyphenoxy)-4'(3,4-dicarboxyphenoxy)diphenyl-2,2-propane dianhydride; etc., and mixtures of such dianhydrides.

In addition, aromatic bis(ether anhydride)s also included by the above formula are shown by Koton, M. M.; Florinski, F. S.; Bessonov, M. I.; Rudakov, A. P. (Institute of Heteroorganic Compounds, Academy of Sciences, U.S.S.R.), U.S.S.R. Pat. No. 257,010, issued Nov. 11, 1969. Also, dianhydrides are shown by M. M. Koton, F. S. Florinski, Zh Org. Khin, 4(5), 774 (1968).

Organic diamines of the above formula include, for example, m-phenylenediamine, p-phenylenediamine, 4,4'diaminodiphenyl propane, 4,4'-diaminodiphenyl methane, benzidine, 4,4'-diaminodiphenyl sulfide, 4,4'-diaminodiphenyl sulfone, 4,4'-diaminodiphenyl ether, 1,5-diaminonaphthalene, 3,3'-dimethylbenzidine, 3,3'-dimethoxybenzidine, 2,4'-bis(beta-amino-t-butyl)toluene, bis(p-beta-amino-t-butylphenyl)ether, bis(p-beta-methyl-o-aminophenyl)benzene, 1,3-diamino-4-isopropylbenzene, 1,2-bis(3-aminopropoxy)ethane, m-xylylenediamine, p-xylylenediamine, 2,4-diaminotoluene, 2,6-diaminotoluene, bis(4-aminocyclohexyl)methane, 3-methylheptamethylenediamine, 4,4-dimethylheptamethylenediamine, 2,11-dodecanediamine, 2,2-dimethylpropylenediamine, octamethylenediamine, 3-methoxyhexamethylenediamine, 2,5-dimethylhexamethylenediamine, 2,5-dimethylheptamethylenediamine, 3-methylheptamethylenediamine, 5-methylnonamethylenediamine, 1,4-cyclohexanediamine, 1,2-octadecanediamine, bis(3-aminopropyl)sulfide, N-methyl-bis(3-aminopropyl)amine, hexamethylenediamine, heptamethylenediamine, nonamethylenediamine, decamethylenediamine, bis(3-aminopropyl)tetramethyldisiloxane, bis(4-aminobutyl)tetramethyl disiloxane, and the like, and mixtures of such diamines.

In general, the reactions can be advantageously carried out employing well-known solvents, e.g., o-dichlorobenzene, m-cresol/toluene, etc., in which to effect interaction between the dianhydrides and the diamines, at temperatures of from about 100° to about 250° C. Alternatively, the polyetherimides can be prepared by melt polymerization of any of the aforementioned dianhydrides with any of the aforementioned diamine compounds while heating the mixture of the ingredients at elevated temperatures with concurrent intermixing. Generally, melt polymerization temperatures between about 200° to 400° C. and preferably 230° to 300° C. can be employed. Any order of addition of chain stoppers ordinarily employed in melt polymerization can be employed. The conditions of the reaction and the proportions of ingredients can be varied widely depending on the desired molecular weight, intrinsic viscosity, and solvent resistance. In general, equimolar amounts of diamine and dianhydride are employed for high molecular weight polyetherimides, however, in certain instances, a slight molar excess (about 1 to 5 mol percent) of diamine can be employed resulting in the production of polyetherimides having terminal amine groups. Generally, useful polyetherimides have an intrinsic viscosity greater than 0.2 deciliters per gram, preferably 0.35 to 0.6 or 0.7 deciliters per gram or even higher when measured in m-cresol at 25° C.

Included among the many methods of making the polyetherimides are those disclosed in U.S. Pat. Nos. 3,847,867, 3,847,869, 3,850,885, 3,852,242 and 3,855,178. These disclosures are incorporated herein in their entirety by reference for the purpose of teaching, by way of illustration, general and specific methods for preparing polyetherimides suitable for the blends of this invention.

A convenient method for preparing the polymeric blends of polycarbonates and polyamides of the present invention is to premix the constituents, (that is, the polycarbonate, the polyamide and the polymeric compatibilizing agent) in the proper weight proportions and in finely divided form to produce a substantially homogeneous dry mixture which is then introduced into a compounding extruder, heated to a molten mass and extruded. Desirably, the ingredients, in a powder or granule state, are blended in a low intensity mixer, such as a ribbon blender, for an effective period of time until a substantially uniform or homogeneous mixture is provided. While the amount of time required to produce the substantially homogeneous mixture can vary widely, desirable results have been obtained when the mixing of the dry ingredients in the ribbon blender is from about 2 to about 5 minutes, and more desirably from about 2 to about 3 minutes.

The dry-blended mixture is fed to a compounding extruder, which serves to heat the mixture to a substantial homogeneous plasticized mass, which plasticized mass is then extruded through the die head of the extruder into strands and is thereafter chopped into pellets.

A single screw or twin screw extruder or reciprocating mixer, such as a Buss kneader, can be utilized as the compounding extruder. However, a twin screw extruder, such as a Werner Pfleider WP ZSK 83 or Werner Pfleider ZSK 90 twin screw extruder, is preferred because of the high shear obtained on the molten mass in the extruder. In addition, high screw speeds are desired, such as from about 100 to about 300 rpm, to insure that the molten mass is subjected to high shear and to further insure substantially uniform mixing of the constituents of the molten mass.

The compounding extruder is operated at a temperature and pressure sufficient to melt the constituents forming the blend and produce a molten mass which can be extruded. Generally, the compounding extruder is operated at a temperature of from about 480° F. to about 550° F. and at a pressure of from about 500 psi to about 1500 psi, and more desirably at a temperature of about 500° F. and at a pressure of about 1000 psi.

The molten homogeneous mass is advanced through the compounding extruder to the die head where the plasticized homogeneous mass is extruded through a plurality of orifices in the die head into an atmospheric environment as strands. The die head of the compounding extruder is maintained at the same temperature that the molten mass is heated to in the compounding extruder, such as a temperature of from about 480° F. to about 550° F.

As previously stated, the extrudate comprises a plurality of strands. The strands are thereafter chopped into pellets. The pelletizing of the extrudate can be accomplished by a strand cut pelletizer, such as a Cumberland pelletizer (where cooling is accomplished in a water bath prior to feeding the strands through the pelletizer), or by an underwater pelletizer, such as a Gala Unit (where the pellets are cut at the die face). The pelletized polymeric blend of a polycarbonate and a polyamide can thereafter be utilized as feedstock in the fabrication of desired articles through either a molding or extrusion process. Such molding and extrusion processes are well known in the art.

The melt compounded blend of the polycarbonate, the polyamide and the compatibilizing agent prepared in accordance with the procedure set forth above has been found to possess the desired properties of each of the constituents, while substantially eliminating the undesirability properties of such constituents.

In order to more fully describe the present invention, the following examples are set forth. However, it is to be understood that the examples are for illustrative purposes only and are not to be construed as limiting the scope of the present invention as defined in the appended claims.

EXAMPLES

A series of experiments were conducted on articles molded of polymeric materials to determine the chemical and physical properties of the polymeric materials. The polymeric resins used in the fabrication of the articles tested were in a powder of granular state, and were dry blended in a ribbon blender for approximately 3 minutes to insure that the constituents were thoroughly mixed and that a substantially uniform or homogeneous mixture was obtained.

The dry blended mixture was then fed to a twin screw compounding extruder (i.e. a Warner Pfleider WP ZSK 83 extruder) which was operated at approximately 1000 psi and had a production rate of 200 lbs/hr. and a residence time in the extruder of approximately 3 minutes. The screw speed, which was independently controlled relative to the output rate of the extruder, was 150 RPM to insure that a high shear was produced on the molten polymeric mass in the extruder and to further insure that the molten polymeric mass was a substantially homogeneous mass. The molten polymer mass or blend was extruded through the die head of the compounding extruder in the form of strands. The strands were passed through a water bath to cool the strands, and thereafter the strands were cut into pellets with a Cumberland pelletizer.

A typical temperature profile of the compounding extruder, which progressively increases from intake to the die head so as to insure proper melting and mixing of the polymeric constituents and form a substantially homogeneous blend thereof, is as follows:

    ______________________________________                                         Feed       Transition  Metering   Die Head                                     ______________________________________                                         460° F.                                                                            480° F.                                                                             480° F.                                                                            480° F.                               ______________________________________                                    

The pellets obtained from each of the experiments were then molded into articles so that the chemical and physical properties of the polymeric materials, and thus the articles fabricated therefrom, could be determined. Table I sets forth the composition of each of the polymeric materials; and Table II is a compliation of test data relating to physical properties of each of such polymeric materials.

                  TABLE I                                                          ______________________________________                                         Composition of Polymeric Materials (weight percent)                            Polymeric Constituent                                                                          Control  1.    2.   3.  4.   5.                                ______________________________________                                         Polyamide       20       45    30   30  30   15                                (polycaprolactam, i.e.                                                         nylon 6)                                                                       Polycarbonate   80       40    55   60  60   75                                (Ave M.W. of approxi-                                                          mately 30,000)                                                                 Compatibilizing agent*                                                                         --        5     5    0   5    5                                Compatibilizing agent    10    10   10   5    5                                (Maleic anhydride grafted                                                      polymeric blend containing                                                     3 parts by weight maleic                                                       anhydride grafted polypropy-                                                   lene and 2 parts by weight                                                     maleic anhydride grafted                                                       ethylene-propylene rubber                                                      ______________________________________                                          *linear segmented thermoplastic elastomer having an ester segment and a        hard segment of semicrystalline, partially aromatic polyamide, based on        diphenylmethane diisocyanate and marketed by Dow Chemical Company under        the trademark "Estamide 90A".                                            

                                      TABLE II                                     __________________________________________________________________________     Physical Property Data                                                         Physical  Polymer Identification                                               Property  Control*                                                                            No. 1                                                                               No. 2                                                                               No. 3                                                                               No. 4                                                                               No. 5                                       __________________________________________________________________________     Flex Modulus (psi)                                                                       --   330,000                                                                             300,000                                                                             330,000                                                                             360,000                                                                             340,000                                     Tensile Strength (psi)                                                                   --   9,500                                                                               8,800                                                                               9,500                                                                               9,000                                                                               8,400                                       Notched Izod                                                                             --   15   22   8.2  18   19                                          Gardner lmpact                                                                           --   >>320                                                                               >>320                                                                               124  >>320                                                                               >>320                                       __________________________________________________________________________      *Physical properties could not be determined because the resins are            incompatible.                                                            

A second series of tests were conducted to compare the physical and chemical properties of a polycarbonate polymer, a polyamide polymer (nylon 6) and polymeric blends of such polymers containing compatibilizing agents forumalted in accordance with the present invention. Table III sets forth the composition of the polymers; and Table IV is a compilation of the test data obtained on such polymer.

                  TABLE III                                                        ______________________________________                                         Composition of Polymeric Materials (weight percent)                                                            Poly-  Poly-                                                   Con-    Con-    meric  meric                                   Polymeric       trol    trol    Blend  Blend                                   Constituents    #1      #2      No. 6  No. 7                                   ______________________________________                                         Polycarbonate   100     --      65     40                                      (Ave. M.W.                                                                     of approximately                                                               30,000)                                                                        Polyamide       --      100     15     45                                      (polycaprolactam,                                                              i.e. nylon 6)                                                                  Compatibilizing agent*                                                                         --      --      5       5                                      Compatibilizing agent                                                                          --      --      5      10                                      (maleic anhydride grafted                                                      polymeric blend containing                                                     3 parts by weight maleic                                                       anhydride grafted polypropy-                                                   lene and 2 parts by weight                                                     maleic anhydride grafted                                                       ethylene-propylene rubber                                                      Compatibilizing agent                                                                          --      --      10     --                                      (acrylonitrile-butadiene-                                                      styrene toughening agent)                                                      ______________________________________                                          *linear segmented thermoplastic elastomer having an ester segment and a        hard segment of semicrystalline, partially aromatic polyamide, based on        diphenylmethane diisocyanate and marketed by Dow Chemical Company under        the trademark "Estamide 90A".                                            

                  TABLE IV                                                         ______________________________________                                         Physical and Chemical Property Data                                            Polymer Identification                                                                                        Poly-  Poly-                                                                   meric  meric                                    Properties   Control  Control  Blend  Blend                                    Tested       #1       #2       No. 6  No. 7                                    ______________________________________                                         Flex Modulus (psi)                                                                          350,000  400,000  360,000                                                                               340,000                                  Tensile Strength                                                                            9,500    11,900   9,750  10,000                                   (psi)                                                                          Heat Distortion                                                                             260      136      250    200                                      Temperature                                                                    (F.°)                                                                   Notched Izod 12       1.4      25     19.4                                     24 Hour Water                                                                               0.3      2.5      0.4    0.5                                      Absorption                                                                     Chemical Resistance:                                                           Detergent*   Poor     Excellent                                                                               Excellent                                                                             Excellent                                Alcohol      Poor     Excellent                                                                               Excellent                                                                             Excellent                                (10% isopropanol)                                                              Turpentine   Poor     Excellent                                                                               Good   Excellent                                Stress Crack                                                                   Resistance:                                                                    Detergent*   24 hr.   >720 hr. 720 hr.                                                                               720 hr.                                  Alcohol      24 hr.   >720 hr. 720 hr.                                                                               720 hr.                                  (10% isopropanol)                                                              Petroleum    50 hr.   >720 hr. 720 hr.                                                                               720 hr.                                  Distillates**                                                                  Paint Thinner                                                                               24 hr.   >720 hr. 720 hr.                                                                               720 hr.                                  Toluene      15 hr.   >720 hr. 87 hr. 720 hr.                                  ______________________________________                                          *Detergent "Rapid Dri" manufactured by Sanolite Chemical Company.              **"WD40" marketed by the WD40 Company.                                   

A third series of tests were conducted to illustrate the properties of a polymeric blend of a polycarbonate polymer, a polyamide polymer, and a compatabilizing agent of 33.3 weight percent Estamid 90A, and 66.7 weight percent of maleic anhydride grafted ethylene-propylene rubber. The proportions of the components are set forth in Table V, with the Properties listed in Table VI.

                  TABLE V                                                          ______________________________________                                         Polymeric Constituents                                                                            Polymeric Blend No. 8                                       ______________________________________                                         Polycarbonate      45                                                          Polyamide          40                                                          Compatibilizing agent - Estamid 90A                                                                5                                                          Compatibilizing agent - EP rubber                                                                 10                                                          ______________________________________                                    

                  TABLE VI                                                         ______________________________________                                         Properties             Polymeric                                               Tested                 Blend No. 8                                             ______________________________________                                         Flex Modulus (psi)     330,000                                                 Tensile Strength (psi) 9,000                                                   HDT (°F.)       205                                                     Notched Izod           17.2                                                    24 hr. H.sub.2 O       0.5                                                     Chemical Resistance:                                                           Detergent              Excellent                                               Alcohol                Excellent                                               Turpentine             Excellent                                               Stress Crack Resistance:                                                       Detergent              >720 hr.                                                Alcohol                >720 hr.                                                Petroleum Distillates  >720 hr.                                                Paint Thinner          >720 hr.                                                Toluene                >720 hr.                                                ______________________________________                                    

The above data clearly indicates the improved physical and chemical properties imparted to the polymeric blends of the present invention, and thus to articles fabricated from such polymeric blends. Further, the unique combination of the polycarbonate, the polyamide and the compatibilizing agent in the formulation of the unique polymeric blends of the present invention provides an unexpected synergistic effect on the chemical and physical properties of the polymeric blends.

Finally, in the compositions of the invention, it is also possible to add other impact modifying agents along with or instead of the previously described maleic anhydride grafted polymers. Suitable impact modifying agents include those disclosed in U.S. Pat. No. 4,174,358, the content of which is expressly incorporated herein by reference thereto.

While it is apparent that the invention herein disclosed it is well calculated to fulfill the objects above stated, it will be appreciated that numerous embodiments and modifications may be devised by those skilled in the art, and it is intended that the appended claims over all such modifications and embodiments as fall within the true spirit and scope of the present invention. 

What is claimed is:
 1. A polycarbonate and polyamide melt compounded blend having improved chemical and physical properties, said blend consisting essentially of:a polycarbonate resin in an amount sufficient to impart a heat distortion temperature of at least about 200° F. the blend; a linear polyamide in an amount sufficient to impart to the blend chemical resistance against solvents and stress cracking agents as well as an impact strength of at least about 15 foot-pounds when measured by the notched izod test; and a polymeric compatibilizing agent comprising a polyetherimide which has at least one functional group soluble in the polycarbonate and at least one functional soluble in the polyamide, each in particulate form, in an amount sufficient to provide a substantially uniform polymeric mixture, wherein the melting point or softening point of the polymeric compatibilizing agent is no greater than the melting or softening point of the polycarbonate and polyamide constituents of the blend, for an effective period of time under low shear conditions so as to form a substantially uniform mixture of the polycarbonate and polyamide components.
 2. The blend of claim 1 wherein the polycarbonate is present in an amount of from about 20 to about 90 weight percent;the polyamide is present in an amount of from about 70 to about 5 weight percent; and the polymeric compatibilizing agent is present in an amount of from about 20 to about 2 weight percent.
 3. The blend of claim 1 wherein the polycarbonate is present in an amount of from about 40 to about 75 weight percent;the polyamide is present in an amount of from about 45 to about 15 weight percent; and the polymeric compatibilizing agent is present in an amount of from about 15 to about 10 weight percent.
 4. The blend of claim 1 wherein said linear polyamide is selected from the group consisting of polyhexamethylene adipamide and polycaprolactam.
 5. The blend of claim 1 wherein said polymeric compatibilizing agent comprises:(a) from about 10 to 100 weight percent of a polyetherimide compound; (b) from 0 to about 50 weight percent of an impact modifying agent; and (c) from 0 to about 80 percent of an alloying agent.
 6. The blend of claim 5 wherein the impact modifying agent comprises a maleic anhydride grafted polymer or polymeric blend.
 7. The blend of claim 6 wherein the maleic anhydride grafted polymer or polymeric blend comprises a mixture of maleic anhydride grafted polypropylene and maleic anhydride grafted enthylene-propylene rubber in a weight ratio of from about 0:1 to about 5:2.
 8. The blend of claim 5 wherein the alloying agent is selected from the group consisting of acrylonitrile-butadiene-styrene terpolymers, styrene-maleic anhydride copolymers, polyester elastomers, methacrylate-butadiene-styrene terpolymers, polymethylmethacrylate, nitrile rubber, ionomers of polyethylene, polyether block amides, and polyphenylene oxide polymers.
 9. The blend of claim 1 wherein said polyamide is a linear polyamide having a molecular weight of at least about 2000 and said polycarbonate has a molecular weight of between about 20,000 to 40,000.
 10. The blend of claim 9 wherein said linear polyamide is selected from the group consisting of polyhexamethylene adipamide and polycaprolactam.
 11. The blend of claim 6 wherein said maleic anhydride grafted polymeric blend is present in the compatibilizing agent in an amount of from about 25 to about 50 weight percent, and said maleic anhydride grafted polymeric blend contains about 3 parts by weight of maleic anhydride grafted polypropylene to about 2 parts by weight of maleic anhydride grafted ethylene-propylene rubber.
 12. A polycarbonate containing melt compounded blend having improved chemical and physical properties, said blend consisting essentially of:from about 20 to about 90 weight percent of a polycarbonate having a molecular weight of from about 20,000 to about 40,000; from about 70 to about 5 weight percent of a linear polyamide having a molecular weight of at least about 2,000; and from about 20 to about 2 weight percent of a polymeric compatibilizing agent of a polyetherimide, polyurethane or a linear segmented thermoplastic elastomer having at least one functional group soluble in the polycarbonate and at least one functional group soluble in the polyamide.
 13. The blend of claim 12 wherein said linear polyamide is polyhexamethylene adipamide or polycaprolactam.
 14. The blend of claim 12 wherein said polymeric compatibilizing agent comprises: (a) from about 10 to 100 weight percent of a polyurethane or linear segmented thermoplastic elastomer having an ester segment and a hard segment of semi-crystalline, partially aromatic polyamide, based on diphenylmethane diisocyanate; (b) from 0 to about 50 weight percent of a maleic anhydride grafted polymeric blend of maleic anhydride grafted polypropylene and maleic anhydride grafted ethylene-propylene rubber; and (c) from 0 to about 80 weight percent of an alloying agent.
 15. The blend of claim 14 wherein the maleic anhydride grafted polypropylene and the maleic anhydride grafted ethylene-propylene rubber are present in a weight ratio of from about 0:1 to about 5:2.
 16. The blend of claim 12 wherein the alloying agent is an acrylonitrile-butadiene-styrene terpolymer, a styrene-maleic anhydride copolymer, polyester elastomer, a methacrylate-butadiene-styrene terpolymer, polymethyl methacrylate, nitrile rubber, an ionomer of polyethylene, a polyether block amide or a polyphenylene oxide polymer.
 17. The blend of claim 12 wherein said linear polyamide has a molecular weight of at least about
 5000. 18. The blend of claim 17 wherein said linear polyamide is polyhexamethylene adipamide and polycaprolactam.
 19. The blend of claim 12 wherein said maleic anhydride grafted polymeric blend is present in the compatibilizing agent in an amount of from about 25 to about 50 weight percent, and said maleic anhydride grafted polymeric blend contains about 3 parts by weight of maleic anhydride granted polypropylene and about 2 parts by weight of maleic anhydride grafted ethylene-propylene rubber.
 20. A polycarbonate and polyamide melt compounded blend having improved chemical and physical properties, said blend consisting essentially of:from about 40 to about 75 weight percent of a polycarbonate having a molecular weight of from about 20,000 to about 40,000; from about 45 to about 15 weight percent of a linear polyamide having a molecular weight of at least about 2,000; and from about 10 to about 15 weight percent of a polymeric compatibilizing agent having at least one functional group soluble in the polycarbonate and at least one functional group soluble in the polyamide so as to form a homogeneous blend with the polycarbonate and polyamide components, said polymeric compatibilizing agent containing:from about 10 to 100 weight percent of a polyurethane or linear segmented thermoplastic elastomer; from 0 to about 50 weight percent of a maleic anhydride grafted polypropylene or maleic anhydride ethylene propylene material; and from 0 to about 80 percent of an alloying agent.
 21. A polycarbonate and polyamide melt compounded blend having improved chemical and physical properties, said blend consisting essentially of:a polycarbonate in an amount sufficient to impart a heat distortion temperature of at least about 200° F. the blend; a linear polyamide in an amount sufficient to impart to the blend chemical resistance against solvents and stress cracking agents as well as an impact strength of at least about 15 foot-pounds when measured by the notched izod test; and a polymer compatibilizing agent of a polytherimide, polyurethane or a linear segmented thermoplastic elastomer having at least one functional group soluble in the polycarbonate and at least one functional soluble in the polyamide in an amount sufficient to provide a homogeneous polymeric blend, wherein the melting point or softening point of the polymeric compatibilizing agent is no greater than the melting or softening point of the polycarbonate and polyamide constituents of the blend, so as to form a homogeneous blend of the polycarbonate and polyamide components.
 22. The blend of claim 21 whereinthe polycarbonate is present in an amount of from about 70 to about 90 weight percent; the polyamide is present in an amount of from about 70 to about 90 weight percent; and the polymeric compatibilizing agent is present in an amount of from about 20 to about 2 weight percent.
 23. The blend of claim 21 whereinthe polycarbonate is present in an amount of from about 40 to about 75 weight percent; the polyamide is present in an amount of from about 45 to about 15 weight percent; and the polymeric compatibilizing agent is present in an amount of from about 15 to about 10 weight percent.
 24. The blend of claim 21 wherein said linear polyamide is polyhexamethylene adipamide or polycaprolactam.
 25. The blend of claim 21 wherein said polymeric compatibilizing agent comprises:(a) from about 10 to 100 weight percent of a polyurethane or linear segmented thermoplastic elastomer having an ester segment and a hard segment of a semi-crystalline, partially aromatic polyamide, based on diphenylmethane diisocyanate; (b) from 0 to about 50 weight percent of a maleic anhydride grafted polymeric blend; and (c) from 0 to about 80 percent of an alloying agent.
 26. The blend of claim 25 wherein maleic anhydride grafted polymeric blend comprises a mixture of maleic anhydride grafted polypropylene and maleic anhydride grafted ethylene-propylene rubber in a weight ratio of from about 0:1 to about 5:2.
 27. The blend of claim 25 wherein the alloying agent is an acrylonitrile-butadiene-styrene terpolymer, a styrene-maleic anhydride copolymer, a polyester elastomer, a methacrylate-butadiene-styrene terpolymer, a polymethylmethacrylate, nitrile rubber, an ionomer of polyethylene, a polyether block amide or a polyphenylene oxide polymer.
 28. The blend of claim 25 wherein said polyamide is a linear polyamide having a molecular weight of at least about 2000 and said polycarbonate has a molecular weight of between about 20,000 to 40,000.
 29. The blend of claim 25 wherein said linear polyamide is polyhexamethylene adipamide or polycaprolactam.
 30. The blend of claim 25 wherein said maleic anhydride grafted polymeric blend is present in the compatibilizing agent in an amount of from about 25 to about 50 weight percent, and said maleic anhydride grafted polymeric blend contains about 3 parts by weight of maleic anhydride granted polypropylene and about 2 parts by weight of maleic anhydride grafted ethylene-propylene rubber.
 31. The blend of claim 23 wherein the compatibilizing agent is a mixture of a linear segmented thermoplastic elastomer having an ester segment and a hard segment of semicrystalline partially aromatic polyamide, based on diphenyl methane diisocyanate, and a maleic anhydride grafted polymeric blend of maleic anhydride grafted polypropylene and maleic anhydride grafted ethylene-propylene rubber, so that the blend has gardner impact test values greater than 320, notched izod impact values greater than 15 foot-pounds and a heat distortion temperature of about 200° F. with excellent chemical and stress cracking resistance.
 32. A polycarbonate and polyamide melt compounded blend having improved chemical and physical properties, said blend consisting essentially of:a polycarbonate in an amount sufficient to impart a heat distortion temperature of at least about 200° F. the blend; a linear polyamide in an amount sufficient to impart to the blend chemical resistance against solvents and stress cracking agents as well as an impact strength of at least about 15 foot-pounds when measured by the notched izod test; and a polymer compatibilizing agent of a linear segmented thermoplastic elastomer having an ester segment and a hard segment of a semi-crystalline, partially aromatic polyamide, based on diphenylmethane diisocyanate, said agent having at least one functional group soluble in the polycarbonate and at least one functional soluble in the polyamide in an amount sufficient to provide a homogeneous polymeric blend, wherein the melting point or softening point of the polymeric compatibilizing agent is no greater than the melting or softening point of the polycarbonate and polyamide constituents of the blend, so as to form a homogeneous blend of the polycarbonate and polyamide components.
 33. The blend of claim 32 wherein the polycarbonate is present in an amount of from about 20 to about 90 weight percent;the polyamide is present in an amount of from about 70 to about 5 weight percent; and the polymeric compatibilizing agent is present in an amount of from about 20 to about 2 weight percent.
 34. The blend of claim 32 further comprising an impact modifying agent in an amount sufficient to increase the impact properties of the blend.
 35. The blend of claim 34 wherein the impact modifying agent is a maleic anhydride grafted polymer blend of a mixture of maleic anhydride grafted polypropylene and maleic anhydride grafted ethylene-propylene rubber in a weight ratio of from about 0:1 to about 5:2.
 36. The blend of claim 32 further comprising an alloying agent.
 37. The blend of claim 36 wherein the alloying agent is acrylonitrile-butadiene-styrene terpolymer, a styrene-maleic anhydride copolymer, a polyestter elastomer, a methacrylate-butadiene-styrene terpolymer, a polymethylmethacrylate, nitrile rubber, an ionomer of polyethylene, a polyether block amide or a polyphenylene oxide polymer. 